Bump urllib3 from 1.25.11 to 1.26.5 in /bdsg/docs

Bumps [urllib3](https://github.com/urllib3/urllib3) from 1.25.11 to 1.26.5.
- [Release notes](https://github.com/urllib3/urllib3/releases)
- [Changelog](https://github.com/urllib3/urllib3/blob/main/CHANGES.rst)
- [Commits](urllib3/urllib3@1.25.11...1.26.5)

---
updated-dependencies:
- dependency-name: urllib3
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <[email protected]>

Author: dependabot[bot]

bdsg/docs/requirements.txt

@@ -24,5 +24,5 @@ sphinxcontrib-jsmath==1.0.1
 sphinxcontrib-qthelp==1.0.3
 sphinxcontrib-serializinghtml==1.1.5
 sphinxcontrib-websupport==1.2.4
-urllib3==1.25.11
+urllib3==1.26.5